1. Technical Field of the Invention
This invention relates generally to universal serial bus devices and integrated circuits used therein.
2. Description of Related Art
Communication systems are known to support wireless and wire lined communications between wireless and/or wire lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks to radio frequency identification (RFID) systems. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, RFID, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), and/or variations thereof.
Depending on the type of wireless communication system, a wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, RFID reader, RFID tag, et cetera communicates directly or indirectly with other wireless communication devices. For direct communications (also known as point-to-point communications), the participating wireless communication devices tune their receivers and transmitters to the same channel or channels (e.g., one of the plurality of radio frequency (RF) carriers of the wireless communication system) and communicate over that channel(s). For indirect wireless communications, each wireless communication device communicates directly with an associated base station (e.g., for cellular services) and/or an associated access point (e.g., for an in-home or in-building wireless network) via an assigned channel. To complete a communication connection between the wireless communication devices, the associated base stations and/or associated access points communicate with each other directly, via a system controller, via the public switch telephone network, via the Internet, and/or via some other wide area network.
For each wireless communication device to participate in wireless communications, it includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). As is known, the receiver is coupled to the antenna and includes a low noise amplifier, one or more intermediate frequency stages, a filtering stage, and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies then. The one or more intermediate frequency stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or intermediate frequency (IF) signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out of band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard.
As is also known, the transmitter includes a data modulation stage, one or more intermediate frequency stages, and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The one or more intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. The power amplifier amplifies the RF signals prior to transmission via an antenna.
In most applications, radio transceivers are implemented in one or more integrated circuits (ICs), which are inter-coupled via traces on a printed circuit board (PCB). The radio transceivers operate within licensed or unlicensed frequency spectrums. For example, wireless local area network (WLAN) transceivers communicate data within the unlicensed Industrial, Scientific, and Medical (ISM) frequency spectrum of 900 MHz, 2.4 GHz, and 5 GHz. While the ISM frequency spectrum is unlicensed there are restrictions on power, modulation techniques, and antenna gain.
As is also known, hand held global positioning system (GPS) receivers are becoming popular. In general, GPS receivers include receiver-processors, and a highly-stable clock, and an antenna that is: tuned to the frequencies transmitted by the satellites. The receiver may also include a display for providing location and speed information to the user. Many GPS receivers can relay position data to a PC or other device using a US-based National Marine Electronics Association (NMEA) protocol.
As IC fabrication technology continues to advance, ICs will become smaller and smaller with more and more transistors. While this advancement allows for reduction in size of electronic devices, it does present a design challenge of providing and receiving signals, data, clock signals, operational instructions, etc., to and from a plurality of ICs of the device. Currently, this is addressed by improvements in IC packaging and multiple layer PCBs. For example, ICs may include a ball-grid array of 100-200 pins in a small space (e.g., 2 to 20 millimeters by 2 to 20 millimeters). A multiple layer PCB includes traces for each one of the pins of the IC to route to at least one other component on the PCB. Clearly, advancements in communication between ICs are needed to adequately support the forth-coming improvements in IC fabrication.
Therefore, a need exists for intra-device wireless communications and applications thereof.